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Fixed: Why iPhone 7 No 4G Signal

If there is only 2G signal on your cell phone and no 4G signal, this means that there are some problems in the 4G signal parts. This happens only after your mobile phone is water damaged, and the water intake is in the 4G signal channel.


Open the iPhone 7 and remove the motherboard to observe under HDMI camera stereo microscope, but we can't observe any traces, so we are going to remove the 4G power amplifier chip.

Remove the TDDPA_RF 4G power amplifier chip and measure the resistance value of the pad with Fluke digital multimeter. We found that the value of 11 pin MLB_PA_VBATT is infinitely large to the ground, it seems that the part is broken. As shown in picture 17-9-1.


Connect WUXINJI dongle and check the circuit diagram on computer, we can see some voltage go to TDDPA_RF and MLBPA_RF2 chips, and the MLBPA_RF chip was not installed.

The voltage is PP_PA_VBATT, which is renamed to MLB_PA_VBATT by R7113_RF resistor. The R7113_RF resistance has been corroded under microscope, as shown in picture 17-9-2.


The circuit icon is identified as 0 ohm resistance, so we short connect directly.

Once again testing iPhone 7 4G signal has returned to normal, water damage causes 4G power amplifier power supply is insufficient, so no 4G signal problem caused.

Repair is over here! More iPhone repair information please check on www.vipfixphone.com
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